21 CFR §600.90

1. (a)An applicant may ask the Food and Drug Administration to waive under this section any requirement that applies to the applicant under §§ 600.80 and 600.81. A waiver request under this section is required to be submitted with supporting documentation. The waiver request is required to contain one of the following:
   1. (1)An explanation why the applicant's compliance with the requirement is unnecessary or cannot be achieved,
   2. (2)A description of an alternative submission that satisfies the purpose of the requirement, or
   3. (3)Other information justifying a waiver.
2. (b)FDA may grant a waiver if it finds one of the following:
   1. (1)The applicant's compliance with the requirement is unnecessary or cannot be achieved,
   2. (2)The applicant's alternative submission satisfies the requirement, or
   3. (3)The applicant's submission otherwise justifies a waiver.